feat: 引入可切换星历模型并扩展天象观测链路

- 新增半解析、旧模型、自定义与多源堆叠星历实例，提供 Context、Instance、SPK 读取及状态与视位置计算
- 统一太阳、月球和行星实例接口，扩展黄经穿越、留、相位、最近角距、偕日可见、任意高度升落、轨道节点及凌日等天象查询
- 完善日月食、月掩与凌日的月缘剖面、有限盘面接触、站心修正、局地可见性、全球路径和地图输出
- 新增 SVG、GeoJSON、KML 天象输出及凌日、月掩和月缘地形相关缓存与几何求解
- 新增恒星星表导入与查询，支持 CSV、Hipparcos、BSC5、Stellarium 等格式及名称、交叉标识、锥面检索和星等过滤
- 补充 IAU 2006、地球定向、折射消光、大气观测、轨道传播及半解析行星/月球数据支持
- 将默认未来民用时标切换为 TimeScaleLeapHour，更新 2027–2400 农历速查表、中文日期解析和时区边界处理
- 增加事件基线、跨模型回归、几何边界、月缘地形和输出契约测试，完善中英文手册、示例资源、NOTICE 与忽略规则

basic/topocentric_horizontal.go

@@ -0,0 +1,90 @@
+package basic
+
+import (
+	"math"
+
+	"b612.me/astro/internal/ephem"
+	. "b612.me/astro/tools"
+)
+
+// topocentricHourAngleDec 由地心视赤经、视赤纬（度）与地心距（AU）给出观测者处的站心时角与站心视赤纬（度）。
+// 恒星时只算一次，视差修正与时角共用；观测者取海拔 0，海拔对太阳系天体视差的影响可忽略。
+func topocentricHourAngleDec(utcJD, lon, lat, ra, dec, distanceAU float64) (hourAngle, topocentricDec float64) {
+	gast := ApparentSiderealTime(UTC2UT1(utcJD)) * 15
+	topocentricRA, topocentricDec := topocentricRaDecWithSidereal(ra, dec, lat, lon, gast, distanceAU, 0)
+	return Limit360(gast + lon - topocentricRA), topocentricDec
+}
+
+// horizontalAltitude 时角、赤纬、纬度（度）转高度角 / altitude from hour angle, declination and latitude.
+func horizontalAltitude(hourAngle, dec, lat float64) float64 {
+	return ArcSin(Sin(lat)*Sin(dec) + Cos(dec)*Cos(lat)*Cos(hourAngle))
+}
+
+// horizontalAzimuth 时角、赤纬、纬度（度）转方位角，北起向东 / azimuth from north through east.
+func horizontalAzimuth(hourAngle, dec, lat float64) float64 {
+	tanAzimuth := Sin(hourAngle) / (Cos(hourAngle)*Sin(lat) - Tan(dec)*Cos(lat))
+	azimuth := ArcTan(tanAzimuth)
+	if azimuth < 0 {
+		if hourAngle/15 < 12 {
+			return azimuth + 360
+		}
+		return azimuth + 180
+	}
+	if hourAngle/15 < 12 {
+		return azimuth + 180
+	}
+	return azimuth
+}
+
+// planetApparentRaDecDistanceNWithInstance 行星地心视赤经、视赤纬与几何地心距，三者取自同一次求值。
+func planetApparentRaDecDistanceNWithInstance(index int, jde float64, n int, inst *Instance) (ra, dec, distanceAU float64) {
+	geo, _, distanceAU, ok := planetApparentPositionWithInstance(index, jde, n, inst)
+	if !ok || math.IsNaN(geo.lo) || math.IsNaN(geo.bo) {
+		return math.NaN(), math.NaN(), math.NaN()
+	}
+	ra, dec = planetApparentRaDecFromLoBo(jde, geo.lo, geo.bo)
+	return ra, dec, distanceAU
+}
+
+func planetTopocentricHourAngleDecN(index int, localJD, lon, lat, timezone float64, n int, inst *Instance) (float64, float64) {
+	utcJD := localJD - timezone/24.0
+	ra, dec, distanceAU := planetApparentRaDecDistanceNWithInstance(index, UTC2TT(utcJD), n, inst)
+	return topocentricHourAngleDec(utcJD, lon, lat, ra, dec, distanceAU)
+}
+
+// planetHeightN 行星站心视高度角（度，不含折射）/ topocentric planet altitude without refraction.
+func planetHeightN(index int, localJD, lon, lat, timezone float64, n int, inst *Instance) float64 {
+	hourAngle, dec := planetTopocentricHourAngleDecN(index, localJD, lon, lat, timezone, n, inst)
+	return horizontalAltitude(hourAngle, dec, lat)
+}
+
+// planetAzimuthN 行星站心方位角（度）/ topocentric planet azimuth.
+func planetAzimuthN(index int, localJD, lon, lat, timezone float64, n int, inst *Instance) float64 {
+	hourAngle, dec := planetTopocentricHourAngleDecN(index, localJD, lon, lat, timezone, n, inst)
+	return horizontalAzimuth(hourAngle, dec, lat)
+}
+
+// sunTopocentricHourAngleDecN 太阳站心时角、站心视赤纬与地日距 / topocentric solar hour angle, declination and distance.
+func sunTopocentricHourAngleDecN(jd, lon, lat, tz float64, n int, inst *Instance) (hourAngle, dec, distanceAU float64) {
+	utcJD := jd - tz/24.0
+	ra, dec, distanceAU := hSunApparentRaDecDistanceN(UTC2TT(utcJD), n, inst)
+	hourAngle, dec = topocentricHourAngleDec(utcJD, lon, lat, ra, dec, distanceAU)
+	return hourAngle, dec, distanceAU
+}
+
+// sunAzimuthN 地距只用于视差，矢量视位置可用时直接取其距离，省去一次地距求值。
+func sunAzimuthN(jd, lon, lat, tz float64, n int, inst *Instance) float64 {
+	utcJD := jd - tz/24.0
+	tt := UTC2TT(utcJD)
+	var ra, dec, distanceAU float64
+	if lo, bo, _, dist, ok, err := vectorApparentWithInstance(ephem.Sun, tt, n, inst); err != nil {
+		return math.NaN()
+	} else if ok {
+		ra, dec = LoBoToRaDec(tt, lo, bo)
+		distanceAU = dist
+	} else {
+		ra, dec, distanceAU = hSunApparentRaDecDistanceN(tt, n, inst)
+	}
+	hourAngle, topocentricDec := topocentricHourAngleDec(utcJD, lon, lat, ra, dec, distanceAU)
+	return horizontalAzimuth(hourAngle, topocentricDec, lat)
+}